In the parent U.S. patent application, Ser. No.07/849,973, filed Mar. 12, 1992, I describe a reactor cell that is used to epitaxially grow a thin film by organo-metallic chemical vapor deposition (OMCVD), alternatively called metalorganic vapor phase epitaxy (MOVPE). That reactor can accommodate one wafer at a time and thus is appropriate for research and other applications not requiring a high throughput of wafers.
I describe there in general terms a rotating susceptor which holds a single wafer and rotates it while the gases used in OMCVD flow over the wafer. It is called a susceptor because, in addition to holding the wafer, it is made of graphite and can be inductively heated by an RF coil located outside the reactor cell, thereby controllably heating the wafer to the desired deposition temperature.
Frijlink has disclosed a similar though more complex wafer holder in U.S. Pat. No. 4,961,399 and in "A new versatile, large size MOVPE reactor," Journal of Crystal Growth, volume 93, 207-215, 1988. Frijlink's wafer holder is intended for large-scale production of layered wafers and can accommodate seven wafers in a planetary structure. Seven rotating disks, each holding a wafer, are supported on a rotating platform. In each case, spiral channels are formed in the otherwise planar structure supporting the disks or the platform. Gas flowing through the spiral channels frictionally engage through viscous laminar flow the overlying, planar bottom surfaces of the disks or platform, thereby rotating them. The gas forms a gas foil beneath the entire disk or platform, thereby supporting them.
Frijlink's wafer holder is not appropriate for a susceptor intended for small-scale production of one wafer at a time. The planetary structure is overly complex, and its design is predicated on the circularly symmetrical and radially outward flow of the OMCVD reaction gases over the seven wafers. In contrast, in a reactor of the type I have described, the reaction gases flow linearly over the single wafer. Also, often a small susceptor is vertically tilted by a few degrees so as to intercept the flow of the reaction gases, to thereby counteract any reactive depletion of the gas flow. Several aspects of Frijlink's design may cause problems if his wafer holder is tilted. Frijlink's article and U.S. patent do not disclose full details on the supply and discharge of the rotator gas, but it appears to discharge radially from the ends of the spirals.